SiteCheck

Look up domain registration (RDAP) and DNS

domain

Read-only

Domain lookup over RDAP (the successor of WHOIS) and DNS: registered or available, registrar, creation, update and expiry dates, days until expiry, age, status codes, DNSSEC, name servers, plus whether it resolves (IPv4/IPv6) and its mail servers. Any TLD with an RDAP service; others are inferred from DNS. Related tools on this server, for a different need: domain_typosquat when you need to list lookalike domains of a brand and their DNS records. Price: $0.002 in USDC per successful call, paid with x402 (Base, Solana or Arc); failed calls are not charged.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "domain": "<domain>"
    },
    "name": "domain"
  }
}

Input Schema

Name	Required	Description	Default
`domain`	Yes	Domain or URL, e.g. example.com or https://www.example.com/page

Output Schema

Name	Required	Description	Default
`dns`	No
`note`	No
`dnssec`	No
`domain`	No
`source`	No
`ageDays`	No
`createdAt`	No
`expiresAt`	No
`registrar`	No
`updatedAt`	No
`registered`	No
`nameServers`	No
`statusCodes`	No
`availability`	No
`rdapAvailable`	No
`daysUntilExpiry`	No
`registrarIanaId`	No
`registeredDomain`	No
`registrantCountry`	No
`registrantOrganisation`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 14, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "ageDays": {},
+    "availability": {},
+    "createdAt": {},
+    "daysUntilExpiry": {},
+    "dns": {},
+    "dnssec": {},
+    "domain": {},
+    "expiresAt": {},
+    "nameServers": {},
+    "note": {},
+    "rdapAvailable": {},
+    "registered": {},
+    "registeredDomain": {},
+    "registrantCountry": {},
+    "registrantOrganisation": {},
+    "registrar": {},
+    "registrarIanaId": {},
+    "source": {},
+    "statusCodes": {},
+    "updatedAt": {}
+  },
+  "type": "object"
+}

First observedOct 8, 2026

TDQS

A4.1/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With readOnlyHint and openWorldHint already declared, the description still adds meaningful behavior: the RDAP-first / DNS-fallback data path (so results may be inferred rather than authoritative), and the billing model ($0.002 USDC per successful call via x402 on Base, Solana or Arc; failures not charged). It does not cover rate limits, error semantics, or what an unavailable domain returns, which keeps it below a 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The capability statement is front-loaded and the long field enumeration earns its length by telling the agent exactly what it gets back. The related-tool and pricing sentences are separate and clearly scoped. Minor redundancy: the return-field list partly duplicates what the output schema already declares.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists so return shape needn't be spelled out, and the description nevertheless covers coverage limits, fallback behavior, cost, and one sibling alternative. What's missing is any handling of the closely related dns/subdomains/ssl siblings and of failure or empty-result cases.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

One parameter with 100% schema description coverage, including an example of both accepted forms (bare domain and full URL). The description adds nothing about the parameter beyond the schema, so the high-coverage baseline of 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Specific verb+resource ('Domain lookup over RDAP ... and DNS') with an explicit enumeration of the facts returned: registration status, registrar, dates, days-to-expiry, age, status codes, DNSSEC, name servers, resolution, mail servers. The scope line ('Any TLD with an RDAP service; others are inferred from DNS') further pins down what the tool actually covers.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It routes the agent away from domain_typosquat with an explicit condition ('when you need to list lookalike domains of a brand and their DNS records'), which is real alternative-routing. The gap is that the highly overlapping siblings dns, subdomains, ssl and certs are never mentioned, so an agent must guess whether a plain DNS question belongs here or in dns.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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